Flue pipe heat exchanger



FIG. 1 is a perspective view of a flue pipe heat exchanger, showing my new design;

FIG. 2 is a front elevational view, the rear elevational view being substantially identical thereto;

FIG. 3 is a top plan view, thereof;

FIG. 4 is an elevational view of one side, the opposite side view being substantially identical thereto;

FIG. 5 is a bottom plan view; and,

FIG. 6 is a perspective view as FIG. 1, but taken to a reduced scale, the broken line representation of the flue damper handle and the stove being included solely for illustrative purposes, forming no part of the claimed design. 

The ornamental design for a flue pipe heat exchanger, as shown and described. 